Series editors' preface - Wood Tools

er of defects and repairs, and the suitability of
the material for interior or exterior use, or
immersion in water etc. The precise form in
which this is expressed differs between countries.
2.6.3 Reconstituted wood products
The desire to extend and modify natural wood
sizes and properties and the need to use manufacturing
waste and residues and smaller and
lower grade trees to produce more versatile
and more consistent products has lead to a vast
array of materials known as wood composites
or reconstituted wood products. Wood composites
can be broadly grouped into fibre
products on one hand and solid wood composites
on the other.
Fibre products include cardboard or pasteboard,
low density fibreboard and medium
density fibreboard (MDF) and hardboards (e.g.
Masonite). In this class of product, wood is
broken down to its individual constituent
wood cells or fibres and is then reformed to
the desired shape with or without pressure by
re-establishing chemical bonding of lignin
between the fibres with little or no added resin
binder.
In solid wood composites, often referred to
as particle boards, particles, chips, flakes, shavings
and other reduced dimensions of whole
wood are re-bonded using a resin adhesive.
These materials are classified by particle type,
by adhesive type, by density, and by strength.
Uniform properties and reduced dimensional
response are typical of these materials but
increasingly they are being engineered for specific
purposes. See Schniewind (1989) for further
information.
2.7 Wooden structures
Furniture is generally expected to be functionally
sound, fit for its intended purpose, good to
look at, strong enough to withstand applied
loads during a useful lifetime, able to accommodate
fluctuations in environmental conditions,
affordable and reasonably transportable.
Except for a few turned or carved items, very
few pieces of furniture are able to meet these
criteria when formed from a single piece of
wood. For example, the most beautiful cuts of
wood are frequently the least stable, the least
Wood and wooden structures 89
strong and also the rarest and most expensive.
They are often more effectively used as
veneers. Wood is comparatively weak perpendicular
to the grain in both tension and compression.
Dimensional change is greater at
right-angles to the grain than parallel to it.
Hence, over the centuries a seemingly bewildering
variety of methods of joining pieces of
wood together has evolved in an attempt to
optimize the production and performance of
wooden structures. New and more complex
forms of wood products are constantly being
developed and with them new ways of joining
pieces together.
It is necessary to understand something of
the nature of joined wooden constructions if
the conservator is to recognize and reduce
potential dangers to wooden structures from
use, display, transport etc. An overview of the
main types of joints used in cabinetmaking is
followed by a review of the critical factors that
determine the success of any given joint with
a more detailed analysis of some representative
joints. This review is illustrative rather than
exhaustive, dealing with basic considerations
and leaving the reader to apply them to specific
situations.
2.7.1 Types of joints
Any junction between two components or
materials that are intended to stay together
could be considered a joint. Joints may rely on
adhesion (e.g. butt joints) or they may be
mechanically interlocked (e.g. dovetail joints)
or they may involve some form of mechanical
fastening such as screws, nails or other more
specialized hardware. Many specialized types
of worked or interlocking joints have been
developed for use in joining wood in cabinetmaking
and these can be classified into three
main groups: widening joints; angle or box
joints; and framing joints.
Widening joints are used to produce wide
boards from a number of narrow boards by
joining them edge to edge. Examples of widening
joints are shown in Figure 2.23.
Angle joints are generally used for fixing
together pieces which have their faces at rightangles
and edges flush. This includes corner
angle joints used in box-like constructions such
as solid cabinets, boxes and drawers and joints
where one piece meets another, with the faces